On the department's complaint data sheet, inspectors said they found that the damage to the window — spandrel glass located between the 9th and 10th floor — was "unrelated to the settlement and tilting" of the problem-plagued tower. The department noted that its decision was based on a report from Allana Buick & Bers, the same firm that evaluated another Millennium Tower window crack on the 36th floor.

A department spokesman told the San Francisco Chronicle that the latest crack has been taped and boarded up, thereby presenting no danger to the public below. The cause of the most recently discovered crack has not been identified yet, according to the San Francisco Examiner, but a window washer reportedly saw it a few years ago. Its position between floors meant that residents could not see it.

Dive Insight:

Allana Buick & Bers found that the 36th floor crack was an isolated incident caused by some exterior impact, according to a letter from the Millennium Tower Association to city building inspectors, and that "no further structural investigation of the curtain wall assembly" was necessary.

The same firm previously determined that gaps found between the building's façade and structure — a result of the building's settlement — could create a means for smoke and fire to circumvent the building's fire safety systems. City fire officials slapped the Millennium with a violation earlier this year requiring management to fix it or provide a qualified third-party engineer's verification that the gaps did not create a fire danger.

Another engineers' review of the Millennium Tower found that the building was sound and could likely withstand a major earthquake, which is a real concern for any structure in San Francisco. In fact, in early October, San Francisco city officials released its Tall Buildings Strategy, which recommends a wide range of changes to building regulations so that structures are better prepared for seismic events.

In addition to beefing up the city's seismic codes, the report also advocates for changes to codes involving foundations and geotechnical issues, most likely a nod to the Millennium Tower, which is not anchored in bedrock and is expected to continue to sink an inch a year, beyond the current 18 inches it has already dropped in its footprint thus far.